Effect of deuteron temperature on iron forbidden-line intensities in rf-heated tokamak plasmas.

Abstract

Two line ratios, the forbidden line at 845.5 A\r{} (2s${}^{2}$2p ${}^{2}$${P}_{1/2}$--2s${}^{2}$2p ${}^{2}$${P}_{3/2}$) to the allowed line at 135.7 A\r{} (2s${}^{2}$2p ${}^{2}$${P}_{1/2}$--2s2${p}^{2}$ ${}^{2}$${D}_{3/2}$) in Fe xxii and the forbidden line at 592.1 A\r{} (2s${}^{2}$2${p}^{4}$ ${}^{3}$${P}_{2}$--2s${}^{2}$2${p}^{4}$ ${}^{1}$${D}_{2}$) to the forbidden line at 1118.2 A\r{} (2s${}^{2}$2${p}^{4}$ ${}^{3}$${P}_{2}$--2${s}^{2}$2${p}^{4}$ ${\mathrm{}}^{3}$${P}_{1}$) in Fe xix, have been measured as ion-temperature-sensitive line ratios during rf heating in the Princeton Large Torus. The results indicate that deuteron collisions in plasmas of high deuteron temperature have a noticeable effect on the intensity of the forbidden lines. Measured relative intensities are compared with values from level-population calculations, which include deuteron collisional excitation between the levels of the ground configuration. The agreement between the observed and calculated ratios is within 30%. A method for deuteron (or proton) temperature measurement in tokamak plasmas is discussed.